Thirty-five new events add to previous discoveries, bringing the total number of gravitational signals detected so far by the global network of Virgo and LIGO interferometers to 90. The results of Virgo and LIGO observations from November to March 2020 were published today.
“Among the new discoveries, for the first time we have confidently observed a binary system with a compact star or black hole 10% heavier than our Sun orbiting a much heavier black hole with a mass of thirty Suns” : explains Boris Goncharov, researcher at the Gran Sasso Science Institute, member of Virgo. “The publication – he continues – is a real milestone for the entire field of Gravitational Wave astronomy. It summarizes the results of the longest and most productive series of observations of a global network of gravitational wave detectors located in Italy, the United States and Japan ”.
The Gravitational Waves of the Universe
Most of the new signals come from the coalescence of two black holes that spiral, whirl and merge, causing perturbations of the space-time fabric, capable of generating one of the most powerful Gravitational Wave emissions in the Universe. Two signals appear instead to come from the coalescence of a neutron star and a black hole. Finally, it is not clear whether another event, revealed in February 2020, comes from a pair of black holes or from a mixed pair formed by a black hole and a neutron star. The results, published today (third catalog from the first revelation in 2015), reveal additional properties of the population of black holes and neutron stars that allow us to understand how the most massive stars live and die.
Data recorded from November 2019 to March 2020
In addition to publishing the results of the observation campaign, also today the scientific collaborations LIGO, Virgo and KAGRA have released all the calibrated data, recorded by the LIGO and Virgo detectors from November 2019 to March 2020. This will allow the entire research community to perform independent analysis and verification, and perhaps contribute to new discoveries that will further enrich the wealth of scientific results.
The Catalog published today offers an overview of these catastrophic cosmic events inaccessible through light. And among the 90 signals revealed some emerge as mass records or with peculiar properties that challenge our models and our knowledge.
Gravitational signals associated with gamma-ray bursts
Concurrently with the release of the new gravitational transient catalog, the collaboration also published the latest results on the joint search for gravitational signals associated with gamma-ray bursts. From the detection of GW170817 we know that an electromagnetic emission associated with Gravitational Waves may exist and the combined study of these two messengers represents the dawn of a new astronomy. In particular, in this study, the researchers exploit the temporal and spatial location of the electromagnetic signal provided by orbiting telescopes to more accurately analyze the data collected by ground-based interferometers. This allows us to check, with greater precision than real-time analysis, if there is actually a gravitational signal in correspondence with the gamma-ray burst.
“The search for Gravitational Wave signals coinciding with the emission of gamma-ray bursts allows us to investigate more deeply the nature of the cataclysmic events associated with them” explains Samuele Ronchini, PhD student at the Gran Sasso Science Institute, who actively contributed to the process of analyses. Then he adds: “Although during the third phase of Ligo-Virgo observation no coincidence of signals was detected, with this study it is possible to obtain details on the distribution of gamma-ray bursts on cosmological scales, their abundance in the local Universe, or even to investigate gamma-ray bursts of low brightness, a class of objects that, to date, are largely unexplored ”.